[Margie909]

I have the Caterpillar C15 engine. I hear something that keeps running for about 10 minutes after I shutdown the engine. It sounds like an electric fuel pump or a fan with a bad bearing, sound is most pronounced at the rear passenger side corner near the engine air intake.  It varies in speed, speed oscillates up and down,and sometimes even shuts off for a few seconds before coming back on. Anybody have any idea what this might be?
Engine does not have to warm for this to occur. Yesterday I started the engine and pulled the coach out of my storage building, shut it down, and I had the noise. Engine was still cool to the touch.
If I throw the chassis battery switch to off it stops immediately.
I've spoke to both Newell and Cat and neither have any idea what it could be.
It doesn't seem normal. but everything seems to work OK, so I hate to throw money at it until I identify the problem.

[bikestuff]

Aqua hot running for some reason? Depending on the coach, the AH exhaust could be right there.

[Richard]

Do you hear the noise if you turn the key to on, but do not start the engine?

Would you characterize it as loud, or just audible?

Is it coming from under the coach, like around the rear axle? The hydraulic cooling fans are under there and they are loud.

Bill’s coach has a bay at the right rear that has all manner of the Valid gizmos in there for slide seals. I have heard strange noises in that bay.

[Margie909]

No, it’s not the aqua hot.
It is rather loud, sound like it is a variable speed motor, you can hear speed change, sometimes it goes off for 30 seconds or so then restarts. I noticed I am also getting a red led light on the rear of the voltage regulator while this is happening.
If I throw battery disconnect to.off sound stops, and I can turn back on, and no sound.
It’s not the hydraulic fans, sound is in engine compartment, not from under coach.
The valid gizmos for slides are located forward about mid coach, it’s not them.
Could it be something to do with the exhaust regen on the cat engine??

[Richard]

That's good info, but I'm out cause I only have experience with the Detroits.

[DK on the road]

I would tend to think it your onto something with the Regen system. I've been around Semi trucks and heavy equipment with all different kind of regen systems. Some did make noise to keep them cool, even before they were hot, because they create extreme heat during the their processing. Your regen would need to be on the driver side rear between the Radiator and engine on the exhaust system. Most systems only go into "noise making" or are activated once they have hit some criteria, for example, Hour meter, build up on a sensor of certain particulate. They must complete their cycle as from what I've seen.

Can you send pictures of what you think is making noise, maybe it can be identified that way

My coach is prior to regen, but I have the C15. Not sure what is the first year of regen.

Keep us posted on what you find.

[Margie909]

Well, took coach to Cat, and noise is coming from regen compressor. (yea, I didn't know it had one either).
Apparently I have one of the first regen engines, parts are for the most part not available for the old system.
the updated regen system will cost between $6 & 8 K total parts and labor. With a questionable outcome.
New systems have not been reliable.
A truck driver friend suggested to me that some people have done a software delete of the regen and gutted the particulate filter, effectively making the engine a non regen piece.
I'm sure the EPA frowns on this, but what can you do?
Has anyone had any experience with this issue?
PM me if you can help.

[DK on the road]

Depending on what state you register the Coach in, deletion could be an option. If you are required to have inspections, you will need to make sure its all working as designed. You may be able to ask EPA about your issue. I know that they have offered assistance to truck owners in the form of $'s to restore or repair a system. An example was in CA where along with our California Air Resources Board (CARB) they offered between 60k to 80K to owners of trucks towards the purchase of a new truck if the old truck met some criteria, like fresh engine in the last few years and very few miles annually are expected out of the truck. They offered $'s also to older engines in newer chassis (gliders). They have also given waivers due to very low mileage usage, or special circumstances . 

 All of this may bring attention to yourself and sometimes it easier to ask for forgiveness than permission.

I would want to keep my final decision between me and a new owner of my Coach, if or when I ever sold it. 

My 2 cents. 

[Richard]

Not trying to be a wise guy, but some info is needed to make the picture more clear. Is the sound normal, or is something broken? If so what is broken?

The generic answer from the dealer that most parts are not available doesn’t sound like that dealer wanted to fool with it. Did the dealer specifically say what part you needed? Did the dealer read the computer for codes?

The guru forum is all about finding solutions for our issues that the mainstream doesn’t want to fix, doesn’t know how to fix, or wants a fortune to experiment.

Have you googled this issue? You can’t have the only Cat engine with this configuration.

I would also call Cat and talk to internal service. And I would find a way to contact Brett Wolfe. He is active on both the IRV2 and Rv.net forums. He is MR CAT.

[Margie909]

Richard
Thanks for you critical view and response, it is most unhelpful.
No the noise is not normal, yes the dealer read the codes.
Dealer was willing to continue to work on it, but wanted me aware cost could be between $6&8K.
So I ask him to stop while I explored other options than to replace a defective system with a new system that has been prone to failure also.
Thank you for the suggestion to contact Brett Wolfe.
That was the only piece of your response that might be helpful.